many people have said that bettas build bubble-nests because they are happy and healthy. this is not completely true. bettas build bubble-nests simply out of instinct. i have seen bettas at walmart hanging on to life in their little cups sitting under their bubble-nests.which is not suitable for them to make them in my opinion.:( but when you take good care of them and they are happily swimming around in their new tank, building bubble-nests, that is the right place for them to build them. :)